Transfer robot and robot system

ABSTRACT

A transfer robot includes one arm, another arm, a motor, and a brake. The another arm is connected to the one arm via a shaft such that the another arm is rotatable relatively with respect to the one arm around a shaft axis of the shaft. The motor includes a rotor rotatable around the shaft axis to rotate the another arm around the shaft axis, and a stator connected to the one arm. The brake is provided at the another arm to apply a force to the stator so as to suppress relative rotation between the stator and the rotor when electric power is not supplied to the motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of the U.S. patentapplication Ser. No. 16/435,565, filed Jun. 10, 2019, which claimspriority under 35 U. S. C. § 119 to Japanese Patent Application No.2018-133294, filed Jul. 13, 2018. The contents of these applications areincorporated herein by reference in their entirety.

BACKGROUND Technical Field

An embodiment disclosed herein relate to a transfer robot and a robotsystem.

Related Art

Conventionally, a transfer robot such as a horizontal articulated robotthat transfers an object to be transferred is known. Further, JapanesePatent Application Laid-Open No. 2005-039047 describes a substratetransfer robot that transfers a substrate as an object to be transferredand incorporates a motor of a finished product in an arm.

SUMMARY

According to one aspect of the present invention, a transfer robotincludes one arm, another arm, a motor, and a brake. The another arm isconnected to the one arm via a shaft such that the another arm isrotatable relatively with respect to the one arm around a shaft axis ofthe shaft. The motor includes a rotor rotatable around the shaft axis torotate the another arm around the shaft axis, and a stator connected tothe one arm. The brake is provided at the another arm to apply a forceto the stator so as to suppress relative rotation between the stator andthe rotor when electric power is not supplied to the motor.

According to another aspect of the present invention, a transfer robotincludes one arm having a first connection portion, another arm, and amotor. The another arm has a second connection portion that is connectedto the first connection portion of the one arm via a shaft such that theanother arm is rotatable relatively with respect to the one arm around ashaft axis of the shaft. The motor is provided at the first connectionportion of the one arm. The motor includes a rotor rotatable around theshaft axis to rotate the another arm around the shaft axis, and a statorconnected to the first connection portion of the one arm. The firstconnection portion of the one arm projects toward the another arm andhas a thickness larger than a thickness of a portion other than thefirst connection portion of the one arm. The another arm has anotherportion which projects toward the one arm and which has a thicknesslarger than a thickness of the second connection portion of the anotherarm.

According to further aspect of the present invention, a transfer robotincludes one arm, another arm, a motor, and a lift portion. The anotherarm is connected to the one arm via a shaft such that the another arm isrotatable relatively with respect to the one arm around a shaft axis ofthe shaft. The motor includes a rotor rotatable around the shaft axis torotate the another arm around the shaft axis, and a stator connected tothe one arm. The lift portion is configured to raise and lower the onearm and the another arm and includes a built-in motor integrated withthe lift portion. The built-in motor is configured to rotate the onearm.

According to the other aspect of the present invention, a transfer robotincludes one arm, another arm, and a motor. The another arm is connectedto the one arm via a shaft such that the another arm is rotatablerelatively with respect to the one arm around a shaft axis of the shaft.The motor is provided at the one arm and includes a rotor rotatablearound the shaft axis to rotate the another arm around the shaft axis.The shaft includes a first shaft portion and a second shaft portion. Thefirst shaft portion is fixed to the one arm and has an axis coaxial withthe shaft axis. The second shaft portion is fixed to the another arm andis connected to the first shaft portion via a bearing such that thesecond shaft portion is rotatable around the shaft axis relatively withrespect to the first shaft portion.

BRIEF DESCRIPTION OF DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1 is a schematic view showing an outline of a transfer robot.

FIG. 2 is a cross-sectional view of a built-in motor.

FIG. 3 is a perspective view of the transfer robot.

FIG. 4 is a side view of a first arm, a second arm, and a hand.

FIG. 5 is a perspective view of the hand.

FIG. 6A is a first perspective view of the first arm.

FIG. 6B is a second perspective view of the first arm.

FIG. 7A is a first schematic view of the second arm.

FIG. 7B is a second schematic view of the second arm.

FIG. 8A is a perspective view of a lift portion.

FIG. 8B is a schematic view of a lift portion.

FIG. 9 is a perspective view showing a second arm according to amodification.

FIG. 10 is a block diagram of a robot system.

DETAILED DESCRIPTION

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

A transfer robot and a robot system disclosed in the present applicationwill be described in detail below, with reference to the accompanyingdrawings. Herein, this invention is not limited to the embodimentdescribed below.

In the embodiment described below, although expressions such as“parallel”, “center”, “symmetry”, “reverse direction”, and “cylinder”may be used, it is not necessary to strictly meet these states. That is,each expression mentioned above shall accept deviations, such asmanufacture accuracy, installation accuracy, processing accuracy, anddetection accuracy.

First, an outline of a transfer robot 10 according to the embodimentwill be described with reference to FIG. 1. FIG. 1 is a schematic viewshowing the outline of the transfer robot 10. FIG. 1 is a perspectiveview of the transfer robot 10 viewed obliquely from above and anexploded perspective view of a first arm 11 (see S1 of FIG. 1).

As shown in FIG. 1, the transfer robot 10 includes a main body 15installed on a floor surface and the like and a lift portion 16 risingand lowering with respect to the main body 15. The lift portion 16raises and lowers the first arm 11 and a second arm 12 which arehorizontal link arms. A hand 13 is provided on the tip end side of thesecond arm 12. The hand 13 can hold an object to be transferred such asa substrate for semiconductor.

Although two hands 13 are shown in FIG. 1, one or three or more hands 13may be provided. Although the two arms (the first arm 11 and the secondarm 12) are shown as horizontal link arms in FIG. 1, three or morehorizontal link arms may be provided.

Here, the transfer robot 10 includes an arm-integrated built-in motor150 as shown in S1 of FIG. 1. FIG. 1 exemplifies a case where the firstarm 11 includes the built-in motor 150 which causes the second arm 12 topivot.

Specifically, the built-in motor 150 includes a stator holding portion11 h formed in the arm and a stator portion (a stator) 100 held by thestator holding portion 11 h. The built-in motor 150 further includes abase 120 and a rotor portion (a rotor) 110 supported by the base 120 androtated relative to the base 120.

Here, the stator portion 100 and the base 120, which are components thatdo not rotate relative to the stator holding portion 11 h, may becollectively referred to as the stator portion 100. That is, among thecomponents of the built-in motor 150, the components that do not rotaterelative to the stator holding portion 11 h may be collectively referredto as the “stator portion 100”, and the components that rotate relativeto the stator holding portion 11 h may be collectively referred to asthe “rotor portion 110”.

Thus, when the component that does not rotate is referred to as thestator portion 100 and the component that rotates is referred to as therotor portion 110, it can be said that the built-in motor 150 has ashape in which the rotor portion 110 is embedded in a recess between anon-rotating shaft (shaft portion 122) and a magnetic field generatingportion (motor core 100 a and motor winding 100 b) in the stator portion100. That is, the rotor portion 110 is embedded in a hollow regionwithin the thickness of the stator portion 100, so that the built-inmotor 150 achieves a reduction in height of the motor.

An attachment portion 113 which rotates together with the rotor portion110 serves as a lid that covers an opening on the second arm 12 side inthe stator holding portion 11 h. The base 120 serves as a lid thatcovers an opening on the opposite side to the second arm 12 in thestator holding portion 11 h. The second arm 12 is attached to theattachment portion 113.

As shown in S1 of FIG. 1, the stator portion 100, the rotor portion 110,and the base 120 are accommodated in the stator holding portion 11 h.That is, the built-in motor 150 uses the stator holding portion 11 hformed in the first arm 11 instead of a case for accommodating thestator portion 100, the rotor portion 110 and the base 120.

As described above, since the transfer robot 10 includes thearm-integrated built-in motor 150, the arm can be miniaturized ascompared with the configuration in which a so-called finished motorhaving a case is used. This makes it possible to contribute to thinningof the arm and narrowing of the width of the arm.

The built-in motor 150 does not have a built-in reduction gear and anexternal reduction gear. Therefore, the built-in motor 150 can directlycause the arm (the second arm 12 in FIG. 1) to pivot. For this reason,as compared with the configuration in which a reduction gear is used,vibration, an operation error, and a mechanical loss can be suppressed.

Hereinafter, the configuration of the built-in motor 150 will bedescribed in more detail with reference to FIG. 2. FIG. 2 is across-sectional view of the built-in motor 150. FIG. 2 shows across-sectional view cut along a plane including the axis of rotation ofthe second arm (the axis of rotation of the built-in motor 150) andalong the extending direction of the first arm 11.

As shown in FIG. 2, the stator holding portion 11 h formed at an end ofthe first arm 11 has a substantially cylindrical shape that protrudes tothe upper surface side of the first arm, and the stator portion 100 isfitted to the inner periphery by so-called shrink fitting or the like.For example, when the stator portion 100 at normal temperature isinserted into the heated stator holding portion 11 h, the stator holdingportion 11 h contracts in a cooling process to hold the stator portion100. The stator portion 100 may be fixed to the stator holding portion11 h with an adhesive. Alternatively, the stator portion 100 may befixed to the stator holding portion 11 h by inserting a pin or the likeradially from the outer peripheral side of the stator holding portion 11h toward the motor core 100 a of the stator portion 100.

First, the stator portion 100 will be described. The stator portion 100is integrally solidified by molding, for example, the motor core 100 aon which a silicon steel plate is stacked and the motor winding 100 bwound around teeth of the motor core 100 a with a resin or the like andis formed into a cylindrical shape. The motor winding 100 b generates amagnetic field by energization. The motor winding 100 b may be woundaround a plurality of bobbins made of resin or the like, and the bobbinsmay be attached to the teeth. The motor core 100 a may have a corelessshape without teeth (inner core), and in the stator portion 100, themotor winding 100 b may be molded on an inner periphery of an outercore.

The stator portion 100 has a cylindrical shape, and has the outerperipheral side in contact with the stator holding portion 11 h and theinner peripheral side facing the outer peripheral side of the rotorportion 110 at an interval. That is, in the built-in motor 150, thestator portion 110 normally accommodated in the case is accommodated inthe stator holding portion 11 h of the first arm 11.

A winding cable 100 c for energizing the motor winding 100 b is guidedto a proximal end of the first arm 11 via an internal space (an internalspace below the stator holding portion 11 in FIG. 2) which does notinterfere with the rotor portion 110 on the inner peripheral side of thestator portion 100. Although the winding cable 100 c is accessible frombelow the first arm 11, this point will be described later withreference to FIG. 6.

Next, the rotor portion 110 will be described. The rotor portion 110 hasa cylindrical shape and includes a cylindrical shaft portion 111corresponding to a yoke and a magnet 112 fixed to the outer peripheralside of the shaft portion 111 with an adhesive or the like. Each of themagnets 112 has, for example, a rectangular shape in which the directionalong the axis of rotation of the rotor portion 110 is longitudinal andthe direction along the outer periphery is lateral, and the magnets 112are spread across the entire outer periphery of the shaft portion 111 atpredetermined intervals.

On the other hand, the inner peripheral side of the shaft portion 111 isfixed to the outer peripheral side of the rotating portion 123 in thebase 120. That is, the rotor portion 110 rotates around a rotationcenterline of the rotating portion 123. Here, the rotation centerline ofthe rotating portion 123 corresponds to the axis of rotation of thesecond arm 12 described above.

The attachment portion 113 having a through hole 113 h is fixed to anend surface of the shaft portion 111 on the second arm 12 side (upperend surface in FIG. 2). Here, the attachment portion 113 is used to fixthe second arm 12. The attachment portion 113 also serves as a lid forclosing an opening on the second arm 12 side in the stator holdingportion 11 h.

Next, the base 120 will be described. As shown in FIG. 2, the base 120fixed to a tip end portion of the first arm 11 has a shape in which ahollow cylinder stands up from a disk having a through hole in a centralportion thereof. The base 120 includes an encoder portion 121, a shaftportion 122, and a rotating portion 123.

The encoder portion 121 closes an opening (a lower opening in FIG. 2) onthe opposite side of the second arm 12 in the stator holding portion 11h. On the upper surface side of the encoder portion 121, a processingsubstrate 121 e of the encoder is provided.

On the lower surface side of the rotating portion 123 which rotates withthe rotor portion 110, a disk having a repeating pattern such as slitsand irregularities is provided along the circumferential direction. Onthe upper surface side of the processing substrate 121 e, a lightemitting portion and a light receiving portion are provided, forexample. The processing substrate 121 e detects reflected light in whichlight emitted from the light emitting portion toward the rotatingportion 123 is reflected by the above-described pattern to detect astate of rotation of the rotor portion 110.

As shown in FIG. 2, an encoder cable 121 c is connected to theprocessing substrate 121 e, and power supply to the processing substrate121 e and output of signals such as detection results are performed. Theencoder cable 121 c is guided to the proximal end of the first arm 11via an internal space of the stator holding portion 11 h below the rotorportion 110. Although the encoder cable 121 c is accessible from belowthe first arm 11, this point will be described later with reference toFIG. 6.

Here, the built-in motor 150 does not have a reduction gear and directlycauses the second arm 12 to pivot. In the second arm 12, the turningangle is limited to less than 360 degrees by a mechanical stopper or thelike. Therefore, the built-in motor 150 does not make one rotation.

Generally, in a motor that makes one or more rotations, the encoderdetects how many rotations the motor has made from a reference position,and stores the detection result. For this reason, the rotating portion123 is usually provided with a disk magnetized with a mark thatindicates that one rotation has made, and the processing substrate 121 eis usually provided with a circuit that detects magnetic force and avolatile memory that records the number of rotations. Then, a battery isprovided which energizes the volatile memory via the encoder cable 121c. The battery is provided, for example, on the inner side surface ofthe main body 15 (see FIG. 1) in consideration of maintainability.

On the other hand, since the rotation of the built-in motor 150 is lessthan one rotation, it is not necessary to provide the above-described“magnetized disk” in the rotating portion 123. In addition, the circuit,volatile memory, and battery described above are also unnecessary.Therefore, with the built-in motor 150, the structure can be simplified,which can also contribute to cost reduction and miniaturization.

The shaft portion 122 has a cylindrical shape rising from the encoderportion 121, and has an axial length which protrudes from the first arm11 and reaches the inside of the second arm 12. A cylindrical cableguide 12 g fixed to the second arm 12 is inserted into the innerperipheral side of the shaft portion 122.

A cable in the second arm 12 is routed inside the first arm 11 via thecable guide 12 g. As described above, by using the cable guide 12 g, itis possible to prevent rubbing of the cable and the shaft portion 122accompanying turning of the second arm 12.

On the outer peripheral side of the shaft portion 122, a first bearingb1, a spacer bs, and a second bearing b2 are provided. Here, the innerperipheral sides of the first bearing b1 and the second bearing b2 arefixed to the shaft portion 122. The spacer bs is used to maintain adistance between the first bearing b1 and the second bearing b2 at apredetermined interval.

A bearing presser 122 a is provided on the tip end side (the secondbearing b2 side) of the shaft portion 122. Here, when assembling, thefirst bearing b1, the spacer bs, and the second bearing b2 are insertedinto the rotating portion 123, and the rotating portion 123 into whichthe bearing and so on are inserted is inserted into the shaft portion122. Each part is assembled by attaching the bearing presser 122 a. Thebearing presser 122 a and the shaft portion 122 may be collectivelyreferred to as the shaft portion 122.

On the other hand, the rotating portion 123 is fixed to the outerperipheral side of the first bearing b1 and the second bearing b2. Therotating portion 123 has a cylindrical shape, and while the innerperipheral side is fixed to the outer peripheral sides of the firstbearing b1 and the second bearing b2, and the outer peripheral side isfixed to the inner peripheral side of the rotor portion 110.Consequently, the rotor portion 110 is rotated relative to the base 120.

Thus, the first bearing b1 and the second bearing b2 rotatably supportthe rotor portion 110. Since the base 120 includes the bearings, theconfiguration of the rotor portion 110 can be simplified, and, at thesame time, assemblability of the built-in motor 150 can be improved.

As shown in FIG. 2, the first bearing b1 and the second bearing b2 areaccommodated in a thickness (thickness in the direction in alignmentwith the axis of rotation of the rotor portion 110) range of thecylindrical stator portion 100. By thus arranging the bearing thatallows the rotor portion 110 to rotate, it is possible to reduce theheight of the built-in motor 150.

Here, when the rotor portion 110 is assembled to the base 120, forexample, the shaft portion 111 and the rotating portion 123 are fastenedwith a bolt or the like. Thus, the rotor portion 110 is fixed to therotating portion 123. The rotor portion 110 may be fixed to the rotatingportion 123 by adhesion or the like.

Thus, the stator portion 110 is fixed to the stator holding portion 11 hfrom above the first arm 11, and the base 120 is fixed to the statorholding portion 11 h from below the first arm 11. Since the rotorportion 110 is fixed to the base 120 from above the first arm 11, thebuilt-in motor 150 is completed.

Although FIG. 2 shows the case where the first arm 11 includes thebuilt-in motor 150 which causes the second arm 12 to pivot, the secondarm 12 may include the built-in motor 150 which causes the second arm 12to pivot. This point will be described later with reference to FIG. 9.

Although FIG. 2 shows the case where the bearings (the first bearing b1and the second bearing b2) are provided on the base 120 side and therotor portion 110 rotates relative to the base 120, the bearings may beprovided on the rotor portion 110 side. In this case, the outerperipheral side of the bearing may be fixed to the inner peripheral sideof the shaft portion 111 in the rotor portion 110, and the rotor portion110 to which the bearing is fixed may be fitted to the outer peripheralside of the shaft portion 122 in the base 120.

Although the two bearings (the first bearing b1 and the second bearingb2) are shown in FIG. 2, one or three or more bearings may be provided.The spacer bs provided between the bearings may be omitted.

Although the single built-in motor 150 for arm pivoting is shown in FIG.2, a plurality of the built-in motors 150 may be provided. For example,the built-in motor 150 which causes the first arm 11 to pivot and thebuilt-in motor 150 which causes the second arm 12 to pivot may beprovided at both ends of the first arm 11. The built-in motor 150 whichcauses the second arm 12 to pivot may be provided at the proximal end ofthe second arm 12, and the built-in motor 150 which causes the first arm11 to pivot may be provided at the proximal end of the first arm 11.

Next, the configuration of the transfer robot 10 will be furtherdescribed with reference to FIG. 3. FIG. 3 is a perspective view of thetransfer robot 10. As shown in FIG. 3, the transfer robot 10 includesthe main body 15, the lift portion 16, the first arm 11, the second arm12, and a plurality of the hands 13.

Here, in order to distinguish each hand, capital alphabetic charactersare appended to the end like a hand 13A and a hand 13B, and when notdistinguishing each hand, it is described as the hand 13. In the presentembodiment, the same may be adopted for other components.

Although FIG. 3 shows the transfer robot 10 including the two hands 13Aand 13B, any number of the hands 13 may be provided. Further, it ispreferable that a lift axis A0, a first axis A1, a second axis A2, and athird axis A3 shown in FIG. 3 be parallel to each other.

The main body 15 incorporates a mechanism for raising and lowering thelift portion 16. The lift portion 16 rises and lowers along the liftaxis A0 shown in FIG. 3 and supports the proximal end of the first arm11 rotatably around the first axis A1. The lift portion 16 itself may berotated about the first axis A1.

The first arm 11 supports, at its tip end, the proximal end of thesecond arm 12 rotatably around the second axis A2. The second arm 12supports, at its tip end, the proximal ends of the hands 13A and 13Brotatably around the third axis A3. The hands 13A and 13B include a baseportion 13 a and a fork portion 13 b.

Thus, the transfer robot 10 is a three-link horizontal articulated robothaving the first arm 11, the second arm 12, and the hand 13. Asdescribed above, since the transfer robot 10 has a lift mechanism, thetransfer robot 10 can access objects to be transferred such assubstrates arranged at different heights.

Next, the appearance of the first arm 11, the second arm 12, and thehand 13 will be described with reference to FIG. 4. FIG. 4 is a sideview of the first arm 11, the second arm 12, and the hand 13. FIG. 4shows the first arm 11, the second arm 12, and the hand 13 in the foldedposture.

In FIG. 4, the first axis A1, the second axis A2, and the third axis A3shown in FIG. 3 are shown for reference. The “folded posture” refers toa posture in which the tip end of the second arm 12 faces the proximalend of the first arm 11 and the tip end of the hand 13 faces theproximal end of the second arm 12.

As shown in FIG. 4, the bottom surface side of the first arm 11 issubstantially flat. On the other hand, on the upper surface side, anupper surface of an end on the side of the second axis A2 has a steppedshape higher than an upper surface of an end on the side of the firstaxis A1. As described above, the upper surface of the end on the secondaxis A2 side protrudes toward the second arm 12 in order to dispose thebuilt-in motor 150 shown in FIG. 1 in the first arm 11.

Thus, in the side view, in the first arm 11, thickness of an end (anexample of “a first connection portion”) where the built-in motor 150 isdisposed is larger than thickness of other portions, and the first arm11 has a shape protruding toward the second arm 12.

As shown in FIG. 4, the upper surface side of the second arm 12 issubstantially flat. On the other hand, on the bottom surface side, alower surface of one end on the side of the second axis A2 has a steppedshape higher than a bottom surface of the other end. The reason why thebottom surface of the end on the second axis A2 side is thus recessedfrom the bottom surface of the other end is to avoid the protrudingshape of the first arm 11 described above.

Thus, in the side view, in the second arm 12, thickness on the other endside is larger than thickness on the side of the end (an example of “asecond connection portion”) corresponding to the second axis A2, and thesecond arm 12 has a shape protruding toward the first arm 11. Therefore,a volume of the thick portion can be increased, and it is easy to secureinside a space to store a mechanism for driving the hand 13.

The hand 13 is provided on an upper surface of an end of the second arm12 opposite to the end on the second axis A2 side. The two hands 13 areprovided in order of the hand 13B and the hand 13A as viewed from thesecond arm 12 along the third axis A3.

Next, the configuration of the hand 13 will be described in more detailwith reference to FIG. 5. FIG. 5 is a perspective view of the hand 13.FIG. 5 corresponds to a view of the hand 13 viewed obliquely from above.

As shown in FIG. 5, the hand 13 includes the base portion 13 a and thefork portion 13 b. The proximal end side of the base portion 13 a issupported by the second arm 12 (see FIG. 3) so as to be rotatable aboutthe third axis A3. The fork portion 13 b is provided on the tip end sideof the base portion 13 a, and the tip end side of the fork portion 13 bis bifurcated.

As shown in FIG. 5, a friction portion 13 bb is provided on an uppersurface 13 ba of the fork portion 13 b. For example, the frictionportion 13 bb is an O-ring fixed so as to be partially embedded in agroove formed on the upper surface 13 ba.

As a material of the O-ring, for example, a resin such as silicon can beused. The friction portion 13 bb prevents displacement of a transferredobject such as a substrate by frictional force with the transferredobject. A claw projecting upward may be provided at a tip end 13 bc ofthe fork portion 13 b. This makes it possible to prevent falling of theobject to be transferred.

Although the friction portion 13 bb is illustrated in FIG. 5, a holdingmechanism such as an adsorption mechanism for adsorbing an object to betransferred or a gripping mechanism for gripping an object to betransferred may be used.

Next, the configuration of the first arm 11 will be described in moredetail with reference to FIGS. 6A and 6B. FIG. 6A is a first perspectiveview of the first arm 11, and FIG. 6B is a second perspective view ofthe first arm 11. FIG. 6A corresponds to a perspective view of the firstarm 11 viewed obliquely from above, and FIG. 6B corresponds to aperspective view of the first arm 11 viewed obliquely from below.

As shown in FIG. 6A, the built-in motor 150 is provided at an end on thesecond axis A2 side in the first arm 11. The stator holding portion 11 hcorresponding to the case of the built-in motor 150 protrudes upwardfrom the upper surface of the first arm 11. The attachment portion 113fixed to the shaft portion 111 in the rotor portion 110 (see FIG. 1)rotates around the second axis A2. The second arm 12 is fixed to theattachment portion 113.

The shaft portion 122 (see FIG. 2) in the base 120 (see FIG. 1)protrudes from the attachment portion 113 along the second axis A2.Since the base 120 is fixed to the first arm 11, the shaft portion 122does not rotate. The first axis A1 which is a turning center of thefirst arm 11 is set at an end opposite to the end on the second axis A2side.

FIG. 6B shows the end on the second axis A2 side in the first arm 11 andthe second arm 12. As shown in FIG. 6B, a through hole 120 h is providedin the bottom surface of the encoder portion 121 in the base 120. Thethrough hole 120 h communicates with an opening of the shaft portion 122shown in FIG. 6A.

As shown in FIG. 6B, a groove is formed radially on the bottom surfaceof the encoder portion 121, and the groove serves as an opening 11 g 1connected to a groove communicating with the inside of the first arm 11and opened downward. Therefore, a cable 13 c inside the second arm 12can be routed inside the first arm 11 via the through hole 120 hcommunicating with the shaft portion 122 in the base 120 and the opening11 g 1. That is, the cable 13 c can be accommodated in the outer shapesof the first arm 11 and the second arm 12.

In addition, a groove communicating with the inside of the first arm 11is formed outside the bottom surface of the encoder portion 121, and thegroove serves as an opening 11 g 2 opened downward. Inside the opening11 g 2, the winding cable 100 c extending from the motor winding 100 bin the stator portion 100 and the encoder cable 121 c extending from theencoder portion 121 are accommodated.

That is, the winding cable 100 c and the encoder cable 121 c can berouted inside the first arm 11 via the opening 11 g 2. That is, thewinding cable 100 c and the encoder cable 121 c can be accommodated inthe outer shape of the first arm 11.

As shown in FIG. 6B, a detachable cover 11 uc may be provided to coverthe through hole 120 h, the opening 11 g 1, and the opening 11 g 2. Byremoving the cover 11 uc, an assembly operation of the transfer robot 10can be made efficient, and the maintainability can be improved. On theother hand, by attaching the cover 11 uc, it is possible to preventminute dust and the like from leaking from the inside to the outside ofthe transfer robot 10.

As shown in FIG. 6B, the bottom surface side of the first arm 11 isformed thinner by the thickness of the cover 11 uc. Therefore, even whenthe cover 11 uc is attached to the first arm 11, the bottom surface ofthe first arm 11 can be made flat.

Next, the configuration of the second arm 12 will be described in moredetail with reference to FIGS. 7A and 7B. FIG. 7A is a first schematicview of the second arm 12, and FIG. 7B is a second schematic view of thesecond arm 12. FIG. 7A corresponds to a see-through plan view of theinside of the second arm 12 viewed from the side, and FIG. 7Bcorresponds to a see-through plan view of the inside of the second arm12 viewed from above.

As shown in FIG. 7A, in order to cause the two hands 13A and 13B tooperate independently, the second arm 12 includes two rotary motors M1and M2 and two belts B1 and B2 for respectively transmitting drivingforce of the rotary motors M1 and M2 to the hands 13A and 13B. Unlikethe built-in motor 150 described above, the rotary motors M1 and M2 arefinished motors provided with a case. Such a finished motor is alsoreferred to as a “removable motor”.

Here, the rotary motors M1 and M2 and the belts B1 and B2 areaccommodated in the thick portion of the second arm 12 already describedwith reference to FIG. 4. On the other hand, a rotation suppression unit(an example of a “brake”) 300 is accommodated in a thin portion of thesecond arm 12.

First, a drive mechanism using the rotary motors M1 and M2 and the beltsB1 and B2 will be described. As shown in FIG. 7A, the two rotary motorsM1 and M2 are arranged such that projecting directions of output shaftsS1 and S2 are opposite to each other.

The driving force of the rotary motor M1 is transmitted to a rotatingshaft 201 which causes the hand 13A to pivot around the third axis A3via a pulley P1 attached to the output shaft S1 and the belt B1.

The driving force of the rotary motor M2 is transmitted to a rotatingshaft 202 which causes the hand 13B to pivot around the third axis A3via a pulley P2 attached to the output shaft S2 and the belt B2.

The pulley is each fixed to the rotating shafts 201 and 202, and thedriving force is transmitted via the pulley. Therefore, by adjusting theouter diameter of the pulley, the reduction ratio of the rotary motorsM1 and M2 can be set to any value.

The hand 13A as the upper hand is connected to the cylindrical rotatingshaft 201 fixed to the second arm 12 via a bearing. Therefore, the hand13A pivots as the rotating shaft 201 rotates with along the rotation ofthe rotary motor M1.

A cylindrical cable guide (similar to the cable guide 12 g shown in FIG.2) communicating with the inside of the hand 13A is inserted inside thecylindrical rotating shaft 201. Such a cable guide serves to safelyroute a cable inside the hand 13A into the second arm 12.

The hand 13B as the lower hand is connected to the hollow rotating shaft202 fixed to the second arm 12 via a bearing. Here, the inner diameterof the rotating shaft 202 is larger than the outer diameter of therotating shaft 201 which rotates with the hand 13A.

That is, the rotating shaft 202 and the rotating shaft 201 are arrangedin a double cylinder shape sharing the rotating shaft. As shown in FIG.2, the rotating shaft 202 is disposed on the upper side in the rotatingshaft 201, and only the upper side is formed in a double cylinder shape.Therefore, on the lower side of the rotating shaft 201, the rotatingshaft 201 is not covered with the rotating shaft 202 but exposed, sothat the driving force can be easily transmitted by the belt B1.

As shown in FIG. 7B, shafts S3 and S4 and pulleys P3 and P4 that rotatearound the shafts S3 and S4 are provided inside the belt B1 in order towiden a passing track of the belt B1. Thus, a desired tension can beapplied to the belt B1, and, at the same time, the belt B1 can beprevented from coming into contact with the rotary motor M2. Since therotary motors M1 and M2 can be arranged close to each other vertically,the second arm 12 can be thinned.

Preferably, the output shafts S1 and S2 of the rotary motors M1 and M2are arranged on a center line CL connecting the second axis A2 and thethird axis A3, and the pulleys P3 and P4 are arranged symmetricallyabout the center line CL. This makes it easy to balance a weight balanceof the second arm 12 with respect to the center line CL.

Thus, the belts B1 and B2 are arranged so that at least a part of themnests in top view. Thus, the width of the second arm 12 (the width inthe normal direction of the center line CL) can be reduced.

Next, the rotation suppression unit 300 will be described. As shown inFIG. 7A, the rotation suppression unit 300 includes a friction band B3wound around the outer periphery of the shaft portion 122 of the base120 in the built-in motor 150 which has entered the inside of the secondarm 12. The friction band B3 is connected to one end side of a link L1that pivots around a shaft S6, and the other end side of the link L1 ispivotably connected to a linear motion shaft of a linear motion actuatorM3.

For example, in the friction band B3, at least the surface on the shaftportion 122 side is processed to increase the frictional force. Thefriction band B3 may be formed of a material such as silicone rubberthat originally has a large frictional force.

As the linear motion actuator M3, a mechanism may be used in which alinear motion shaft biased in either the forward or backward directionby a spring or the like is advanced or retracted using anelectromagnetic force. A linear motion motor which can control theamount of advancement and retraction of a linear motion shaft may beused as the linear motion actuator M3.

Here, the attachment portion 113 which rotates with the rotor portion110 in the built-in motor 150 is fixed to the second arm 12. Therefore,if the rotation of the shaft portion 122 is stopped, the pivoting of thesecond arm 12 can be stopped.

That is, the friction band B3 changes its inner diameter as the linearmotion shaft of the linear motion actuator M3 advances and retracts.When the friction band B3 is wound around the outer periphery of theshaft portion 122, the rotation of the shaft portion 122 is stopped bythe frictional force. That is, the rotation of the shaft portion 122 issuppressed. On the other hand, when the friction band B3 is separatedfrom the outer periphery of the shaft portion 122, the rotation of theshaft portion 122 is permitted.

As shown in FIG. 7B, one end of the friction band B3 is fixed to theshaft S7, and the other end is connected to one end of the link L1. Thatis, the friction band B3 has an arc shape along the outer periphery ofthe shaft portion 122 in top view, and elastically deforms when anexternal force is applied.

A biasing force in a counterclockwise direction is applied to the shaftS6, which is a pivot shaft of the link L1, by a spring or the like (seea rotation direction R1). When no electric power is supplied to thelinear motion actuator M3, a linear motion shaft S5 of the linear motionactuator M3 is in an extended state by the biasing force. The frictionband B3 is in a state of being wound around the outer periphery of theshaft portion 122 and suppressing the rotation of the shaft portion 122.

As described above, when a situation such as interruption of a powersupply occurs, relative pivoting between the first arm 11 and the secondarm 12 is suppressed, and the arm can be prevented from continuingunintended movement. When no electric power is supplied to the built-inmotor 150, it is possible to prevent each arm from pivoting due toexternal force or gravity.

For example, at the time of installation of the transfer robot 10, thearm can be prevented from freely pivoting and coming into contact withsurrounding obstacles. When a power failure or the like occurs, it ispossible to prevent the pivoting arm from pivoting as it is.

On the other hand, when electric power is supplied to the linear motionactuator M3, the linear motion shaft S5 contracts against the biasingforce around the shaft S6 (see direction D1). Consequently, the innerdiameter of the friction band B3 spreads and separates from the outerperiphery of the shaft portion 122. Thus, the friction band B3 allowsthe rotation of the shaft portion 122.

The biasing force about the shaft S6 may be reversed (clockwise), andthe movement of the linear motion shaft S5 according to presence orabsence of the power supply may be reversed. A mechanism of the rotationsuppression unit 300 may be a mechanism different from the mechanismshown in FIG. 7A or 7B. For example, a concavo-convex portion may beprovided on the outer periphery of the shaft portion 122, and therotation of the shaft portion 122 may be suppressed by stopping rotationof a gear engaged with the concavo-convex portion.

Thus, by providing the rotation suppression unit 300 in an arm (thesecond arm 12 in FIGS. 7A and 7B) other than the arm having the built-inmotor 150, the arm (the first arm 11 in FIGS. 7A and 7B) provided withthe built-in motor 150 can be miniaturized. The rotation suppressionunit 300 may be provided in the arm (the first arm 11 in FIGS. 7A and7B) having the built-in motor 150.

Next, the lift portion 16 shown in FIG. 1 and the like will be describedin more detail with reference to FIGS. 8A and 8B. FIG. 8A is aperspective view of the lift portion 16, and FIG. 8B is a schematic viewof the lift portion 16. FIG. 8A is a perspective view of the liftportion 16 rising and lowering with respect to the main body 15 asviewed obliquely from above. FIG. 8B corresponds to a see-through planview of the main body 15 viewed from above.

As shown in FIG. 8A, the lift portion 16 rises and lowers with respectto the main body 15 in a direction of the lift axis A0. The lift portion16 has, for example, a cylindrical shape in a portion projecting fromthe main body 15 and includes on its upper end side a liftportion-integrated built-in motor 550 which causes the first arm 11 topivot around the first axis A1. The lift portion-integrated built-inmotor 550 has no case like the built-in motor 150 shown in FIG. 1 andthe like and is a motor of a type which causes an object to be attachedto hold a stator portion 500.

Specifically, the lift portion 16 includes a substantially cylindricalstator holding portion 16 h on the upper end side, and the statorholding portion 16 h substitutes for a case of the built-in motor 550.Specifically, the stator holding portion 16 h holds the inserted statorportion 500, and the rotor portion 510, which rotates with respect tothe stator portion 500, is similarly inserted into the stator holdingportion 16 h.

As described above, the built-in motor 550 includes the stator portion500, the rotor portion 510 that rotates with respect to the statorportion 500, and the stator holding portion 16 h that is formed in thelift portion 16 and that holds the stator portion 500. Here, thebuilt-in motor 550 shown in FIG. 8A is larger in thickness (thicknessalong the lift axis A0 shown in FIG. 8A) than the built-in motor 150shown in FIG. 1 and the like.

This is because the built-in motor 550 that drives the first arm 11requires a larger motor capacity (torque) than the built-in motor 150that drives the second arm 12. That is, by increasing the thickness, itbecomes easy to increase a winding amount and to increase an amount ofpermanent magnet, so that the motor capacity can be increased.

The lift portion 16 may not have a cylindrical shape. For example, thelift portion 16 may have an arbitrary shape such as a rectangularparallelepiped shape. That is, as long as the stator holding portion 16h having a shape that functions as a case of the stator portion 500 andthe rotor portion 510 can be formed, the shape of the lift portion 16can be any shape.

As shown in FIG. 8B, a lift mechanism of the lift portion 16 is storedin the main body 15. The lift portion 16 is supported on the uppersurface side of a movable unit BD5. On the inner wall side of the mainbody 15, a pair of linear guides LG5 extending along the lift axis A0shown in FIG. 8A is provided. The movable unit BD5 is provided with apair of sliders SD5 which slide along the pair of linear guides LG5. Therotor portion 510 is provided with a through hole 510 h. Consequently, acable or the like from the first arm 11 (see FIG. 1) can be guided tothe inside of the main body 15.

The main body 15 is provided with a ball screw BS5 extending along thelift axis A0 shown in FIG. 8A, and the movable unit BD5 rises and lowerswith the rotation of the ball screw BS5. The ball screw BS5 includes apulley P5. The driving force of a rotary motor M5 is transmitted to thepulley P5 via a belt B5, whereby the ball screw BS5 rotates.

As described above, the movable unit BD5 can be raised and lowered bychanging the rotational direction of the rotary motor M5. That is, thelift portion 16 can be raised and lowered. Since the lift portion 16 isguided by the pair of linear guides LG5, the lift portion 16 can riseand lower with high accuracy.

Next, a second arm 12A according to a modification will be describedwith reference to FIG. 9. FIG. 9 is a perspective view showing thesecond arm 12A according to the modification. FIG. 9 corresponds to aperspective view of the second arm 12A as viewed obliquely from below.FIG. 9 shows a case where the built-in motor 150 provided in the firstarm 11 in FIG. 1 is provided in the second arm 12A. The details of thebuilt-in motor 150 have already been described, and therefore thedescription will be omitted as appropriate.

As shown in FIG. 9, the built-in motor 150 is provided at an end on thesecond axis A2 side. The second arm 12A includes a stator holdingportion 12 h and holds the stator portion 100. The attachment directionof the built-in motor 150 is upside down from the case shown in FIG. 1.The attachment portion 113, which rotates with the rotation of the rotorportion 110, is fixed to the upper surface side of the first arm 11 (seeFIG. 1). Thus, when the built-in motor 150 rotates, the second arm 12Apivots relative to the first arm 11 about the second axis A2.

The lower surface side of the second arm 12A provided with the built-inmotor 150 can be made flat according to the maximum thickness shown inFIG. 4. Accordingly, the upper surface side of the first arm 11 fromwhich the built-in motor 150 is omitted can be made flat according tothe minimum thickness. The rotation suppression unit 300 shown in FIG.7A can be provided in the first arm 11.

Although FIG. 9 illustrates the case where the built-in motor 150 isprovided in the second arm 12A instead of the built-in motor 150 shownin FIG. 1, for example, the built-in motor 150 may be provided at theproximal end of the first arm 11 in the same direction as in FIG. 9instead of the built-in motor 550 shown in FIG. 8A.

Next, a robot system 1 including the transfer robot 10 and a controldevice (an example of “control circuitry”) 20 for controlling theoperation of the transfer robot 10 will be described with reference toFIG. 10. FIG. 10 is a block diagram of the robot system 1. Theconfiguration and the like of the transfer robot 10 have already beendescribed, and therefore the configuration of the control device 20 willbe mainly described below. In FIG. 10, an input terminal device such asa so-called pendant connected to the control device 20 is omitted.

As shown in FIG. 10, the control device 20 includes a control unit 21and a storage unit 22. The control unit 21 includes an operation controlsection 21 a and an operation suppression section 21 b. The storage unit22 stores teaching data 22 a. The control device 20 is connected to thetransfer robot 10.

Here, the control device 20 includes, for example, a computer having acentral processing unit (CPU), a read only memory (ROM), a random accessmemory (RAM), a hard disk drive (HDD), an input/output port and the likeand various circuits.

The CPU of the computer reads and executes a program stored in the ROM,for example, to function as the operation control section 21 a and theoperation suppression section 21 b of the control unit 21.

At least one or both of the operation control section 21 a and theoperation suppression section 21 b of the control unit 21 can beconfigured by hardware such as an application specific integratedcircuit (ASIC) or a field programmable gate array (FPGA).

The storage unit 22 corresponds to, for example, a RAM or an HDD. TheRAM or HDD can store the teaching data 22 a. The control device 20 mayacquire the above-described program and various pieces of informationvia another computer connected via a wired or wireless network or aportable recording medium.

The control unit 21 of the control device 20 controls the operation ofthe transfer robot 10 based on the teaching data 22 a. For example, whenan error occurs in the operation of the transfer robot 10, a process ofsuppressing the operation of the transfer robot 10 is performed.

The operation control section 21 a controls the operation of thetransfer robot 10 based on the teaching data 22 a. Specifically, theoperation control section 21 a instructs the motor corresponding to eachaxis in the transfer robot 10, based on the teaching data 22 a stored inthe storage unit 22, to cause the transfer robot 10 to transfer anobject to be transferred such as a substrate. Further, the operationcontrol section 21 a performs feedback control using the encoder valueof the motor, for example, to improve operation accuracy of the transferrobot 10.

The operation suppression section 21 b acquires an operation status ofthe transfer robot 10 from the operation control section 21 a, and forexample when an error occurs in the operation of the transfer robot 10,the operation suppression section 21 b executes an operation suppressionprocess such as stopping the operation of the transfer robot 10. Forexample, the operation suppression section 21 b stops the energizationto the rotation suppression unit 300 shown in FIG. 7A and the like toapply the brake on movement of joints of the transfer robot 10.

Consequently, it is possible to prevent the arm and the like of thetransfer robot 10 from being displaced by an external force or the like.Even when there is no instruction from the control device 20, therotation suppression unit 300 executes rotation suppression operation ifthe energization to the transfer robot 10 is stopped.

The teaching data 22 a is generated in a teaching step of teachingmotions to the transfer robot 10 and is information including a “job”which is a program defining the motion of the transfer robot 10including the movement trajectory of the hand 13 (see FIG. 1). Theteaching data 22 a generated by another computer connected via a wiredor wireless network may be stored in the storage unit 22.

As described above, the transfer robot 10 according to the presentembodiment includes the plurality of horizontal link arms 11 and 12 formoving the hand 13 capable of holding an object to be transferred. Atleast one of the plurality of arms 11 and 12 includes the arm-integratedbuilt-in motor 150 which causes their own or another arm to directlypivot. Thus, with the arm-integrated built-in motor 150, the arms 11 and12 can be miniaturized.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A transfer robot comprising: one arm; another armconnected to the one arm via a shaft such that the another arm isrotatable relatively with respect to the one arm around a shaft axis ofthe shaft; a motor comprising: a rotor rotatable around the shaft axisto rotate the another arm around the shaft axis; and a stator connectedto the one arm; and a brake provided at the another arm to apply a forceto the stator so as to suppress relative rotation between the stator andthe rotor when electric power is not supplied to the motor.
 2. Thetransfer robot according to claim 1, further comprising: a plurality ofhands rotatably connected to the another arm via a second shaft, whereinthe another arm comprises a plurality of removable rotary motors and aplurality of belts therein, and wherein driving force of each of theplurality of removable rotary motors is transmitted to each of theplurality of hands via each of the plurality of belts.
 3. The transferrobot according to claim 2, wherein the plurality of hands include afirst hand and a second hand, wherein the plurality of removable rotarymotors include a first rotary motor and a second rotary motor, the firstrotary motor having a first output shaft projecting in a firstdirection, the second rotary motor having a second output shaftprojecting in a second direction opposite to the first direction, andwherein the plurality of belts include a first belt and a second beltwhich are arranged such that at least a portion of the first belt andthe second belt is nested when viewed along the first direction.
 4. Atransfer robot comprising: one arm having a first connection portion;another arm having a second connection portion that is connected to thefirst connection portion of the one arm via a shaft such that theanother arm is rotatable relatively with respect to the one arm around ashaft axis of the shaft; a motor provided at the first connectionportion of the one arm, the motor comprising: a rotor rotatable aroundthe shaft axis to rotate the another arm around the shaft axis; and astator connected to the first connection portion of the one arm; thefirst connection portion of the one arm projecting toward the anotherarm and having a thickness larger than a thickness of a portion otherthan the first connection portion of the one arm; and the another armhaving another portion which projects toward the one arm and which has athickness larger than a thickness of the second connection portion ofthe another arm.
 5. The transfer robot according to claim 4, furthercomprising: a plurality of hands rotatably connected to the another armvia a second shaft, wherein the another arm comprises a plurality ofremovable rotary motors and a plurality of belts therein, and drivingforce of each of the plurality of removable rotary motors is transmittedto each of the plurality of hands via each of the plurality of belts,and wherein the plurality of removable rotary motors and the pluralityof belts are arranged in the another portion of the another arm.
 6. Thetransfer robot according to claim 2, wherein the stator has a throughhole extending along the shaft axis, and a cable for each of theplurality of removable rotary motors is provided inside the one arm andinside the second arm via the through hole and an opening provided on alower surface side of the one arm.
 7. The transfer robot according toclaim 6, further comprising: a removable cover closing the through holeand the opening.
 8. A transfer robot comprising: one arm; another armconnected to the one arm via a shaft such that the another arm isrotatable relatively with respect to the one arm around a shaft axis ofthe shaft; a motor comprising: a rotor rotatable around the shaft axisto rotate the another arm around the shaft axis; and a stator connectedto the one arm; and a lift portion that is configured to raise and lowerthe one arm and the another arm and that comprises a built-in motorintegrated with the lift portion, the built-in motor being configured torotate the one arm.
 9. The transfer robot according to claim 1, whereinthe stator has a cylindrical shape, the rotor faces an inner peripheralside of the stator, and the motor further comprises a base that supportsthe rotor.
 10. The transfer robot according to claim 9, wherein the basefurther comprises a bearing that rotatably supports the rotor.
 11. Thetransfer robot according to claim 10, wherein the bearing is disposed ina hollow region of the stator.
 12. A robot system comprising: thetransfer robot according to claim 1; and control circuitry configured tocontrol the transfer robot.
 13. The transfer robot according to claim 1,wherein an entirety of the motor is provided inside the one arm.
 14. Thetransfer robot according to claim 1, further comprising: a handconnected to the another arm.
 15. The transfer robot according to claim1, wherein the one arm has an upper surface and the another arm has anlower surface, the upper surface being opposite to the lower surfacewhen the one arm and the another arm overlap, and wherein the shaft axisis substantially perpendicular to the upper surface and the lowersurface.
 16. A transfer robot comprising: one arm; another arm connectedto the one arm via a shaft such that the another arm is rotatablerelatively with respect to the one arm around a shaft axis of the shaft;a motor provided at the one arm and including a rotor rotatable aroundthe shaft axis to rotate the another arm around the shaft axis; and theshaft comprising: a first shaft portion fixed to the one arm and havingan axis coaxial with the shaft axis; and a second shaft portion fixed tothe another arm and connected to the first shaft portion via a bearingsuch that the second shaft portion is rotatable around the shaft axisrelatively with respect to the first shaft portion.
 17. The transferrobot according to claim 1, wherein the brake comprises a friction bandwound around an outer periphery of a shaft portion which has an axiscoaxial with the shaft axis and which is connected to the stator. 18.The transfer robot according to claim 1, wherein the brake is configurednot to suppress the relative rotation when electric power is supplied tothe motor.
 19. The transfer robot according to claim 1, wherein thebrake is provided inside the another arm.
 20. The transfer robotaccording to claim 1, wherein the brake is configured to apply africtional force to the stator.
 21. The transfer robot according toclaim 1, wherein the stator is provided to surround the rotor.